Is it EVER the right decision to take the tunnel?

seriously. this tunnel was designed more poorly than the monorail.

Trip Advisor on Tunneling

I agree with the Trip Advisor report, up to a point. Yes, if you arrive during rush hour, it's probably going to be signicantly faster to take the tunnel to get downtown (assuming that you don't get caught in some gigantic traffic jam on 15). During non-rush hour periods, however, Google maps estimates that it will take you only about 4 minutes longer to get downtown by taking Paradise, and you will save about $16 in fare.

I think that it's significant that the Nevada Taxi Cab Authority appears to use the mileage for the Paradise Rd. when giving estimated fares to downtown.

NTCA Fare Estimates for Las Vegas

has anyone actually been asked if they want to take the tunnel? i have NEVER had a driver ask me and if i dont offer up which way i would like to go, the next thing i know, im in the tunnel.

We stayed at Rio once with a limo from the airport and he took the tunnel.
It was a Rio limo, comped for my friend so I would think that was the best route.

I always end up in the tunnel unless I expressly say, as I'm getting in the cab, "DON'T take the tunnel!"

I've had drivers ask me if I want the shortest or the quickest route. Which is the correct answer so that we don't go in the tunnel? I say the shortest?

Saying "shortest" should keep you out of the tunnel, at least if you are going to the Strip or downtown. Many times the drivers will say "You want me to get you there fast?" If you say "yes," they will see that as their green light to take the tunnel.

Taxi services should charge fixed rates from the airport to any hotel and back. The tourists will know in advance exactly what the ride will cost. The cab company will be motivated to take the best route. Sure, sometimes the cab will be stuck in traffic, but that eventuality would be built into the fixed rate.

This would go a long way toward cleaning up an industry fraught with deceptive practices. The drivers would be motivated to provide fast, fair and freindly service. The tourists start and end their trips with a square deal rather than a rip-off.

I totally agree. Charge me a flat $15, and I'll easily fork over a $5 with out batting an eyeball.